GIS, remote sensing, and analytical hierarchy process (AHP) approach for rainwater harvesting site selection in arid regions: Feija Plain case study, Zagora (Morocco)

The watermelon cultivation industry in Morocco's arid desert regions has experienced swift expansion due to increasing demand both nationally and globally. Nevertheless, this growth has led to the depletion of the already scarce groundwater resources, necessitating a paradigm shift in water resource management. This study adopts an integrated approach, leveraging field measurements, laser diffraction for soil particle size analysis, GIS mapping, and remote sensing, to pinpoint optimal sites for rainwater harvesting (RWH). A comprehensive methodology involving Soil Conservation Service Curve Number (SCS CN), and various conditioning criteria layers (Rainfall, Land Use and Land Cover, Geomorphology, Slope, Topographic Wetness Index, Infiltration number, and Aspect) was applied. The Analytic Hierarchy Process (AHP) assigned weights to criteria, and a Weighted Linear Combination (WLC) approach in GIS produced an RWH suitability map. The map, classified into four zones (unsuitable, low, moderate, and high cover), showed promising potential for 5.24% of the study area. Field data validation after significant rain events confirmed an 86 percent overall map accuracy. Eight recommended RWH sites, including GPS coordinates, are proposed for decision-makers to facilitate strategic implementation, ensuring sustainable water availability for both drinking and irrigation in this arid region.